Improvement in metal-punches



STATES DE LANOY KENNEDY,

OF NEW YORK, N. Y.

IMPROVEMENT IN METAL-PUNCHES.

Specification forming part of Letters Patent No. 161,968, dated April13, 1875; application filed October 22, 1874.

I as are used for punching metals and other substances, of which thefollowing is a description, reference being had to the accompanyingdrawings, forming a part of this specification.

The nature of this invention consists in forming or shaping the ends ofpunches in a winding or spiral manner, by which a continuous shearingcut is performed as the tool is forced or driven into the substance tobe punched, in the same manner that the blades of shears perform theoperation in a straight line, and this applies the same whether the toolbe round, square, or oval.

1n the annexed drawing, Figure 1 represents a face view of a punch soformed; Fig. 2, a side view of the same; and Fig. 3,another side view,showing the face of the chisel or perpendicular cut from A B to thecenter.

In Fig. 2 the cutting-edge is seen to descend from the point A, and windin a spiral or uniform manner around the tool until it has performed itscircuit to the point B, and perpendicular to the starting-point A, thespiral cut extendingto the center of the tool, or as nearly so as may beconsistent with strength. From this it will be seen that only one sideor portion of the cutting-edge of the tool is working at one time, andtherefore the resistance of the metal or other substance is reduced tothe lowest possible point.

I am aware that various methods have been resorted, to to divide theresistancesuch as cutting one part of the face of the tool a littlelower than the other, or making it slightly concave or convex, orbeveling it from one side or edge to the other, which devices, whilethey may, in a measure, reduce the resistance, do not accomplish thedesired end by performing a uniform shearing cut around the entirecircuit of the punch.

What I claim, and desire to secure by Let- -tcrs Patent, is-

The herein described punch, constructed with a cutting-edge extendingfrom the point Ain aspiral direction to B, and from the salient point ofthe spiral to the longitudinal center, as and for the purpose set forth.

DE LANGY KENNEDY.

Witnesses:

OLE H. HOLBERG, D. S. RIDDLE.

